Why Nero message " target SCSI error"

I have one question about my Cd R-W or my software…
after i finished burned sometimes succesfull and sometimes error and apear message " target SCSI error" just it.
but i don’t use any SCSI hardware. Please show me about my problem.
and i also trying NERO 4.08 and All appear same message.

Above my computer
Model : Acer CRW6432 A
Device : ATAPI CD-R/RW 6x4x32
Firmware Revision : 6.BU

Software : NERO Version : bundled
got from acer. PART NO:46.B1004.011

Computer Hardware:
Intel celeron 433 Mhz
64 Mb RAM
hard disk IDE
Cd-Rom Drive IDE